Agaricus Bisporus

>> I was under the assumption that Agaricus Brunescens was the common
>> grocery store mushroom. I could be wrong (I'm not sure I even spelled
>> it right).
>>I thought it was A. campestris.
The name A. campestris was used for a long time to refer to the
cultivated species, despite the fact the the formal description for A.
campestris depicts a mushroom quite different from the "store-bought"
mushroom. Agaricus campestris is really the Meadow Mushroom, a tasty
white mushroom that grows wild around here (New York state) in large
numbers.
Better names for the "store-bought" mushroom are A. brunnescens and A.
bisporus. Which name you choose depends on your ideas about what a
couple of mycologists were really looking at earlier this century.
Charles Horton Peck described A. brunnescens back in 1900, whereas the
name bisporus (as Psalliota hortensis var. bisporus) wasn't published
until 1926, by Jakob Lange. If those two mycologists were really
describing the same fungal species, the International Code of Botanical
Nomenclature specifies that the older name, Peck's A. brunnescens, should
be used. Unfortunately, this is a difficult issue to resolve, because
the specimen on which Peck based his name is in poor shape. Eminent
mycologists have argued both ways.
Although I personally think the latest data points to A. brunnescens Peck
as being more appropriate than A. bisporus (Lange) Imbach, you may want
to examine the arguments and make up your own mind which name to use:
Malloch, D., Castle, A., and Hintz, W. 1987. Further evidence for
Agaricus brunnescens Peck as the preferred name for the cultivated
Agaricus. Mycologia 79: 839-846.
Singer, R. 1984. Agaricus brunnescens Peck and Agaricus bisporus (Lange)
Imbach. Mycotaxon 20: 479-482.
Kathie Hodge
kh11 at cornell.edu